1. Technical Field of the Invention
The present invention relates to novel amino acid compounds, to a process for the preparation thereof and to their use as photoprotecting UV screening agents, in particular when formulated as cosmetic compositions.
The present invention also relates to a regime/regimen employing the aforesaid novel compounds for the protection of the skin and/or hair against the deleterious effects of ultraviolet radiation and for the photoprotection of any other material or substrate which is sensitive to UV radiation (inorganic or organic glasses, plastics, foodstuffs, paints, etc.).
2. Description of the Prior Art
It is known to this art that light radiation of wavelengths of from 280 nm to 400 nm enables human skin to brown and that radiation of wavelengths of from 280 nm to 320 nm, known as UV-B radiation, causes erythemas and skin burns which can harm the development of natural tanning. For these reasons and also for aesthetic reasons, there exists a continual demand for means for controlling this natural tanning, for the purpose of thus controlling the color of the skin; it is thus advisable to screen out this UV-B radiation.
It is also known to this art that UV-A radiation, of wavelengths of from 320 nm to 400 nm, which causes the skin to brown, is apt to also effect a detrimental change therein, especially in the case of sensitive skin or skin which is continually exposed to solar radiation. In particular, UV-A radiation causes a loss of skin elasticity and the appearance of wrinkles, resulting in premature aging. It promotes the triggering of the erythemal reaction or accentuates this reaction in certain individuals and can even be the cause of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons, such as preservation of the natural elasticity of the skin, for example, more and more individuals wish to control the effect of UV-A radiation on their skin. It is thus desirable to screen out the UV-A radiation as well.
Thus, for the purpose of providing protection of the skin and hair against all UV radiation which is as complete and as efficient as possible, sunscreen compositions are typically applied/administered that contain combinations of screening agents active in the UV-A region and screening agents active in the UV-B region.
Benzylidenecamphorsulfonamide compounds derived from amino acids are known to the prior art and, in particular, are described in U.S. Pat. No. 5,004,594 as UV screening agents, especially in the cosmetic field. Other sunscreens derived from amino acids, namely, amide compounds of para-methoxycinnamic acid and of urocanic acid, have also been described, in FR-2,579,461. These amino acid derivatives are capable of absorbing in the UV-B region and/or the UV-A region. They are soluble in those solvents conventionally employed in anti-sun/sunscreen formulations and, in particular, in oils. These exhibit no activity with regard to the scattering of light.
In the field of photoprotection, it has now surprisingly and unexpectedly been determined that certain amino acid compounds, insoluble or substantially insoluble in water and the conventional organic solvents, are capable both of absorbing and of scattering UV radiation in anti-sun/sunscreen formulations. Thus, the subject novel amino acid compounds in accordance with the invention provide a stronger photoprotection in comparison with the known amino acid derivatives.
The present invention thus features compositions well suited for photoprotecting a material/substrate sensitive to ultraviolet radiation, in particular to solar radiation, comprising an effective amount of at least one compound having the structural formula (I): 
in which n is an integer ranging from 1 to 4; and R1 is one of the following radicals of formula (1), (2), (3), (4), (5), (6) or (7): 
in which p is an integer ranging from 1 to 3; R2 is hydrogen, a C1-C8 alkyl radical, a C1-C8 O-alkyl radical, or a C1-C8 O-acyl radical; R3 and R4, which may be identical or different, are each H or halogen or C1-C8 alkyl or alkoxy or a radical of the following formula (8): 
R5 is a hydrogen or halogen atom, a C1-C8 alkyl or alkoxy radical, or a divalent radical: 
R6 is a hydrogen atom, a C1-C8 alkyl radical or a divalent radical: 
with the proviso that at least one of the two substituents R5 and R6 is the divalent radical: 
R7 is a C1-C8 alkyl radical; and the acid or base salts thereof.
More particularly according to the present invention, when the sensitive material/substrate to be protected is human skin and/or hair, the subject compositions are provided in the form of cosmetic compositions comprising, formulated into a topically applicable, cosmetically acceptable vehicle, diluent or carrier therefor, an effective photoprotecting amount of at least one compound of formula (I).
The compounds of formula (I) in accordance with the invention can be provided in the form of a mixture of isomers or of a pure isomer (regio-, enantio- or geometric isomerism).
Exemplary preferred compounds of formula (I) are ornithine (n=3) derivatives and lysine (n=4) derivatives.
More particularly exemplary compounds of formula (I) in accordance with the invention are:
Nxcex5-cinnamoyl-L-lysine;
Nxcex5-(4-methoxycinnamoyl)-L-lysine;
Nxcex5-[4-(4,7,7-trimethyl-3-oxobicyclo[2.2.1]hept-2ylidenemethyl) benzenesulfonyl]-L-lysine.
Nxcex5-Cinnamoyl-L-lysine is described in the article xe2x80x9cSyntheses of photosensitive poly(amino acids)xe2x80x9d, Nasawa M. and Kamogawa H., Bulletin of the Chemical Society of Japan, Vol. 48 (9), pages 2588-2591 (1975). 3-[(1-Oxo-3-phenyl-2-propenyl)amino]-L-alanine and its monohydrochloride have been described in the article xe2x80x9cStructural determinants of inhibitory activity of N3(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid towards glucosamine-6-phosphate synthasexe2x80x9d, Andruszkiewicz R., Polish J. Chem., 67, pages 673-683 (1993).
Accordingly, this invention also features the novel amino acid compounds corresponding to the formula (I) as defined above, with the exception of Nxcex5-cinnamoyl-L-lysine and of 3-[(1-oxo-3-phenyl-2propenyl)amino]-L-alanine and its monohydrochloride.
Too, the present invention features a process for the preparation of the novel compounds of formula (I) described above, comprising:
(a) in a first stage, complexing the NH2xe2x80x94CH(COOH)xe2x80x94 moiety of an amino acid monohydrochloride having the following formula (II): 
xe2x80x83with a copper sulfate in a basic medium (for example, an aqueous sodium hydroxide solution) in the presence of a polar organic solvent (such as tetrahydrofuran, dimethylformamide or acetone);
(b) in a second stage, reacting, in the presence of a polar organic solvent, the copper complex thus obtained with an acid chloride R1COCl or a sulfonyl chloride R1SO2Cl, wherein R1 is as defined above in the formula (I);
(c) in a third stage, recovering, by filtration, the precipitate obtained in stage (b); and
(d) decomplexing the product thus obtained with a sequestering agent (for example, ethylenediaminetetraacetic acid).
These amino acid derivatives are insoluble or substantially insoluble in water and in the conventional organic solvents usual in the cosmetics field, in particular oils.
By the term xe2x80x9cinsoluble or substantially insoluble compoundsxe2x80x9d are intended compounds having a solubility in water of less than 2% by weight, with a solubility in liquid petrolatum of less than 3% by weight and, finally, with a solubility in a mixture of triglyceride esters, such as xe2x80x9cMiglyol 812xe2x80x9d, marketed by Dynamit Nobel, of less than 5%, also by weight.
The amino acid compounds in accordance with the present invention can be reduced to a suitable particulate form by any ad hoc means, such as, in particular, dry milling or milling in a solvent medium, sieving, atomization, micronization or spraying. The mean size of the particles will generally be less than 50 xcexcm and more preferably will range from 0.01 xcexcm to approximately 20 xcexcm.
The amino acid compounds in accordance with the present invention can be used as UV screening agents for the anti-sun/sunscreen protection of the human skin and of the hair. They can also be employed as light photoprotective agents in those industries relating to plastics, textiles, glass (containers, optical glasses, in particular eyeglasses) and other industrial materials/substrates, such as foodstuffs.
The compound or compounds of formula (I) are advantageously formulated into the cosmetic compositions according to the invention in proportions ranging from 0.1% to 20% by weight with respect to the total weight of the composition, preferably from 0.1% to 15%.
The cosmetic compositions of the invention are useful protective compositions for the human epidermis, or for the hair, or as anti-sun/sunscreen compositions.
The anti-sun/sunscreen cosmetic compositions according to the invention can, of course, comprise one or more additional, hydrophilic or lipophilic, organic anti-sun/sunscreen screening agents which are active in the UV-A and/or UV-B regions (absorbers), other than the screening agents indicated above. These additional organic screening agents are advantageously selected, in particular, from among the cinnamic derivatives, dibenzoylmethane derivatives, salicylic derivatives, camphor derivatives, triazine derivatives, such as those disclosed in U.S. Pat. No. 4,367,390, EP-863,145, EP-517,104, EP-570,838, EP-796,851, EP-775,698, EP-878,469 and EP-933,376, benzophenone derivatives, xcex2,xcex2-diphenylacrylate derivatives, benzimidazole derivatives, bisbenzoazolyl derivatives, such as those disclosed in EP-A-0,669,323 and U.S. Pat. No. 2,463,264, bishydroxyphenolbenzotriazole derivatives, such as those described in U.S. Pat. Nos. 5,237,071 and 5,166,355, GB-A-2,303,549, DE-19,726,184 and EP-A-893,119, p-aminobenzoic acid derivatives, or screening hydrocarbonaceous polymers and screening silicones, such as those described, in particular, in WO-93/04665.
Exemplary sunscreens which are active in the UVA and/or UVB regions include:
p-aminobenzoic acid;
oxyethylenated (25 mol) p-aminobenzoate;
2-ethylhexyl p-dimethylaminobenzoate;
N-oxypropylenated ethyl p-aminobenzoate;
glycerol p-aminobenzoate;
homomenthyl salicylate;
2-ethylhexyl salicylate;
triethanolamine salicylate;
4-isopropylbenzyl salicylate;
4-tert-butyl-4xe2x80x2-methoxydibenzoylmethane;
4-isopropyldibenzoylmethane;
2-ethylhexyl 4-methoxycinnamate;
methyl diisopropylcinnamate;
isoamyl 4-methoxycinnamate;
diethanolamine 4-methoxycinnamate;
menthyl anthranilate;
2-ethylhexyl 2-cyano-3,3-diphenylacrylate;
ethyl 2-cyano-3,3-diphenylacrylate;
2-phenylbenzimidazole-5-sulfonic acid and salts thereof;
3-(4xe2x80x2-trimethylammonio)benzylidenebornan-2-one methyl sulfate;
2-hydroxy-4-methoxybenzophenone;
2-hydroxy4-methoxybenzophenone-5-sulfonate;
2,4-dihydroxybenzophenone;
2,2xe2x80x2,4,4xe2x80x2-tetrahydroxybenzophenone;
2,2xe2x80x2-dihydroxy-4,4xe2x80x2-dimethoxybenzophenone;
2-hydroxy-4-(n-octoxy)benzophenone;
2-hydroxy-4-methoxy-4xe2x80x2-methylbenzophenone;
xcex1-(2-oxoborn-3-ylidene)toluene-4-sulfonic acid and soluble salts thereof;
3-(4xe2x80x2-sulfo)benzylidenebornan-2-one and soluble salts thereof;
3-(4xe2x80x2-methylbenzylidene)-d,1-camphor;
3- benzylidene-d,1-camphor;
benzene-1,4-di(3-methylidene-10-camphorsulfonic acid) and soluble salts thereof;
urocanic acid;
2,4,6-tris[p-(2xe2x80x2-ethylhexyl-1xe2x80x2-oxycarbonyl)anilino]-1,3,5-triazine;
2-[p-(tert-butylamido)anilino]-4,6-bis[p-(2xe2x80x2-ethylhexyl-1xe2x80x2-oxycarbonyl) anilino]-1,3,5-triazine;
2,4-bis[4-(2-ethylhexyloxy)-2-hydroxyphenyl]-6(4methoxyphenyl) -1,3,5-triazine;
the polymer of N-[(2- and 4-)[(2-oxoborn-3-ylidene)-methyl]benzyl]acrylamide;
1,4-bisbenzimidazolylphenylene-3,3xe2x80x2,5,5xe2x80x2-tetrasulfonic acid and soluble salts thereof;
2,2xe2x80x2-methylenebis[6-(2H-benzotriazol-2-yl)-4(1,1,3,3tetramethylbutyl) phenol];
the compound 2,2xe2x80x2-methylenebis[6-(2H-benzotriazol-2yl)-4-(methyl)phenol];
polyorganosiloxanes comprising a benzalmalonate functional group;
polyorganosiloxanes comprising a benzotriazole functional group, such as Drometrizole Trisiloxane.
The compositions according to the invention can also include agents for the artificial tanning and/or browning of the skin (self-tanning agents), such as, for example, dihydroxyacetone (DHA).
The cosmetic compositions according to the invention can also include pigments or, alternatively, nanopigments (mean size of the primary particles: generally ranging from 5 nm to 100 nm, preferably from 10 nm to 50 nm) formed of metal oxides which are coated or uncoated, such as, for example, titanium dioxide (amorphous or crystallized in the rutile and/or anatase form), iron oxide, zinc oxide, zirconium oxide or cerium oxide nanopigments or mixtures thereof which are all UV photoprotective agents well known per se. Furthermore, alumina and/or aluminum stearate are conventional coating agents. Such coated or uncoated metal oxide nanopigments are described, in particular, in EP-A-0,518,772 and EP-A-0,518,773.
The compositions of the invention can additionally comprise conventional cosmetic adjuvants and additives selected, in particular, from among fatty substances, organic solvents, thickeners, softeners, antioxidants, opacifiers, stabilizers, emollients, hydroxy acids, antifoaming agents, moisturizing agents, vitamins, fragrances, preservatives, surfactants, fillers, sequestering agents, propellants, basifying or acidifying agents, polymers, colorants, dyes or any other ingredient conventionally included in cosmetics, in particular for the formulation of anti-sun/sunscreen compositions in the form of emulsions.
The fatty substances can be composed of an oil or a wax or mixtures thereof and they also comprise fatty acids, fatty alcohols and fatty acid esters. The oils are advantageously selected from among animal, vegetable, mineral or synthetic oils and, in particular, from among liquid petrolatum, liquid paraffin, volatile or non-volatile silicone oils, isoparaffins, poly-xcex1-olefins, or fluorinated and perfluorinated oils. Similarly, the waxes are advantageously selected from among animal, fossil, vegetable, mineral or synthetic waxes, per se known to this art.
Exemplary organic solvents include the lower alcohols and polyols.
The thickeners are advantageously selected, in particular, from among the crosslinked homopolymers of acrylic acid or from among the modified or unmodified guar gums and celluloses, such as hydroxypropylated guar gum, methylhydroxyethyl-cellulose, hydroxypropylmethyl cellulose or hydroxyethylcellulose.
Too, one skilled in this art will take care to select this or these optional additional compounds and/or the amounts thereof such that the advantageous properties intrinsically associated with the amino acid derivatives in accordance with the invention are not, or are not substantially, detrimentally affected by the envisaged addition or additions.
The compositions of the invention can be formulated according to techniques well known to this art, in particular those suited for the preparation of emulsions of oil-in-water or water-in-oil type.
Such compositions can be provided, advantageously, in the form of a simple or complex emulsion (O/W, W/O, O/W/O or W/O/W), such as a cream, a milk, a gel or a cream gel, a lotion, an ointment, a powder or a solid stick and can optionally be packaged as an aerosol and provided in the form of a foam or spray.
When formulated as an emulsion, the aqueous phase thereof can comprise a nonionic vesicular dispersion prepared according to known techniques (Bangham, Standish and Watkins, J. Mol. Biol., 1965, 13, 238, FR-2,315,991 and FR-2,416,008).
The cosmetic compositions of the invention can be formulated as compositions for protecting the human epidermis or the hair against ultraviolet radiation as an anti-sun/sunscreen composition or as a makeup product.
When the cosmetic compositions according to the invention are formulated for the protection of the human epidermis against UV rays or as an anti-sun/sunscreen composition, same can be provided in the form of a suspension or dispersion in solvents or fatty substances, in the form of a nonionic vesicular dispersion or in the form of an emulsion, preferably of oil-in-water type, such as a cream or a milk, in the form of an ointment, gel, cream gel, solid stick, aerosol foam or spray.
When the cosmetic compositions according to the invention are formulated for the protection of the hair, same it can be provided in the form of a shampoo, lotion, gel, emulsion or nonionic vesicular dispersion and can constitute, for example, a rinse-out composition, to be applied before or after shampooing, before or after dyeing or bleaching and before, during or after permanent waving or hair straightening, a styling or treating lotion or a styling or treating gel, a lotion or a gel for blow drying or hair setting, or a composition for permanent waving or straightening, dyeing or bleaching the hair.
When the subject compositions are suited as products for making up the eyelashes, eyebrows or skin, such as a treatment cream for the epidermis, foundation, lipstick, eyeshadow, face powder, mascara or eyeliner, same can be provided in the anhydrous or aqueous, pasty or solid form, such as oil-in-water or water-in-oil emulsions, nonionic vesicular dispersions, or suspensions.
For example, for the anti-sun/sunscreen formulations in accordance with the invention which include a vehicle of oil-in-water emulsion type, the aqueous phase (comprising in particular the hydrophilic screening agents) generally constitutes from 50% to 95% by weight, preferably from 70% to 90% by weight, with respect to the total weight of the formulation, the oily phase (comprising in particular the lipophilic screening agents) from 5% to 50% by weight, preferably from 10% to 30% by weight, with respect to the total weight of the formulation, and the (co)emulsifier(s) from 0.5% to 20% by weight, preferably from 2% to 10% by weight, also with respect to the total weight of the formulation.
The present invention also features formulating at least one compound of formula (I) into compositions well suited for the photoprotection of industrial materials and substrates which are sensitive to ultraviolet radiation, in particular to solar radiation.
Too, the present invention features formulating at least one compound of formula (I) into cosmetic compositions well suited for the photoprotection of the skin and/or hair against the damaging effects of ultraviolet radiation, in particular solar radiation.
The aforementioned photosensitive industrial materials and substrates can, in particular, be organic and/or inorganic glasses, plastics, textiles, paints, varnishes, foodstuffs, and the like.
The compounds of the invention can be applied in an effective amount onto the surface of said photosensitive industrial materials/substrates or else can be incorporated directly into the composition or body of said industrial materials/substrates.
This invention thus features a technique for the protection of a photosensitive industrial material/substrate against the harmful effects of UV radiation, in particular solar radiation, by incorporating, in said material/substrate, an effective photoprotecting amount of a compound of formula (I).
In another embodiment of the invention, the protection process entails applying, onto the face surface(s) of said photosensitive industrial material/substrate, an effective photoprotecting amount of a compound of formula (I).
In order to further illustrate the present invention and the advantages thereof, the following specific examples are given, it being understood that same are intended only as illustrative and in nowise limitative.